| Abstrakt: |
SUMMARY: With climate change, an aggravation in summer drought is expected in the Mediterranean region. To assess the impact of such a future scenario, we compared the response of Quercus pubescens, a drought‐resistant deciduous oak species, to long‐term amplified drought (AD) (partial rain exclusion in natura for 10 years) and natural drought (ND). We studied leaf physiological and physico‐chemical trait responses to ND and AD over the seasonal cycle, with a focus on chemical traits including major groups of central (photosynthetic pigments and plastoquinones) and specialized (tocochromanols, phenolic compounds, and cuticular waxes) metabolites. Seasonality was the main driver of all leaf traits, including cuticular triterpenoids, which were highly concentrated in summer, suggesting their importance to cope with drought and thermal stress periods. Under AD, trees not only reduced CO2 assimilation (−42%) in summer and leaf concentrations of some phenolic compounds and photosynthetic pigments (carotenoids from the xanthophyll cycle) but also enhanced the levels of other photosynthetic pigments (chlorophylls, lutein, and neoxanthin) and plastochromanol‐8, an antioxidant located in chloroplasts. Overall, the metabolomic adjustments across seasons and drought conditions reinforce the idea that Q. pubescens is highly resistant to drought although significant losses of antioxidant defenses and photoprotection were identified under AD. Significance Statement: Climate change will increase drought episodes, especially in the Mediterranean region. This study investigated Quercus pubescens response to long‐term amplified drought (AD) in natura, focusing on leaf physiological and physico‐chemical traits across seasons and AD. It revealed that seasonal variations influenced leaf metabolism, including leaf cuticular compounds, which are important to cope with drought and thermal stress. Also, AD led to a decrease in net photosynthesis as well as losses in antioxidant defense and photoprotection. [ABSTRACT FROM AUTHOR] |
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